Supercharged silicon

Intel's announcement that it is moving into the 64bit chip arena has well and truly thrown a spanner into the works. Niall Magennis investigates the increasingly complicated future of processors.

When it announced it was going to produce a 64bit chip that would break away from the x86 instruction set of the Pentium family, Intel threw the processor market into turmoil.

Before Intel's Itanium announcement, Risc chips from the likes of Sun, HP, Compaq and IBM dominated the 64bit market. Now, with HP and Compaq phasing out their own chips in favour of the Itanium, the future is unclear for many potential customers.

The Itanium was jointly developed by HP and Intel. It is designed primarily to replace existing 64bit Risc systems and challenge Sun's UltraSparc range of servers in the high-end enterprise market.

The Itanium is the first major chip Intel has produced in recent years that breaks from the x86 instruction set. Although it can run 32bit applications at a much reduced speed using emulation, the Itanium chip uses a completely new instruction set called Explicitly Parallel Instruction Computing (Epic) and so is not truly backwards-compatible.

Epic is designed to have strong parallelism capabilities so the Itanium can perform a number of tasks within a single clock cycle. The chip's 64bit memory addressing capability also means it can use massive amounts of memory - far more than a 32bit processor.

Existing 32bit x86 processors are limited to a relatively small addressing space of up to 4GB of memory. Using a method called bank switching some processors, including Intel's Pentium III and AMD's Athlon, can address more than 4GB of memory, but this harms performance and increases the complexity of the overall hardware design.

Itanium debate

The first generations of Itanium chipsets are expandable to 64GB of memory, but later systems will go way beyond this. However, Itanium is not for everyone and PCs using the processor will not be replacing Pentium or Xeon-based machines on the desktop or in smaller servers.

"For front-end rack-mounted servers or volume departmental servers, Xeon will be there for the foreseeable future," says Chris Hogg, enterprise business manager for Intel. "The place Itanium is going to play is with people replacing expensive proprietary back-end Risc systems with Itanium systems."

The introduction of the Itanium has not been without problems. There has been much criticism that Intel's first Itanium chip, codenamed Merced, is more of a development processor than a true enterprise-ready platform.

Sun, unsurprisingly, has been one of the most vocal critics. "The initial response to the first Itanium-family processor has been somewhat lukewarm," says Jonathan Mills, product marketing manager for Sun. "The introduction of the processor was delayed significantly and a lack of 64bit-capable OS and software in the beginning has muted its introduction.

"The performance of the processor was also below what was expected, which resulted in many server vendors, and Compaq in particular, rearranging their strategies to concentrate on Itanium processors only with the arrival of the McKinley core, expected later this year."

Although Compaq denies it has rearranged its plans, it admits it is mostly developers who are interested in the platform.

Malcolm Cochran, Compaq product manager for Alpha server products, says: "Itanium is very new and although we are offering Itanium platforms, those products are addressing the developer community at the moment because there isn't a plethora of operating systems today that run on Itanium."

Not enough support

Itanium has suffered from a lack of operating system support and major applications. Most analysts believe customers won't seriously examine it until the introduction of McKinley, which offers a huge performance boost over the current Merced chips and should also coincide with major software releases for Itanium from the likes of Microsoft and Oracle.

Among those dare-devils who have already opted for the platform, Linux is the flavour of the month.

"The most popular operating system on it seems to be Linux - a low cost offering - and it really does seem to be a cost driver to move on to Itanium at the moment," says Ian Stevens, industry standards server business manager for Compaq.

"Customers are moving away from Sun boxes. They are doing it with Linux because they've got Unix skills, so they can get what they see as a safe Unix environment up and running quickly."

Stevens' comments fit in nicely with Intel and Compaq's aim of taking on Sun. However, with Stevens admitting he has fewer than 100 customers for Compaq's initial Itanium offering, there is a way to go - especially as UltraSparc is the dominant 64bit platform.

Sun also has the second largest processor design team in the world, behind Intel. It has 1,300 Sparc designers spread across Sunnyvale, Austin and Chelmsford.

"UltraSparc has been there for some time and the track record of that against a new chip like Itanium has been a tricky one for developers," says Sun's Mills. "Itanium runs hot and the experience of the migration is like having a completely new chip in the marketplace.

"You have to recompile everything and that's a very large migration for them to do, whereas with Sparc we can cope with the 64bit migration seamlessly as it is binary-compatible and runs old apps at full speed."

Mills also accuses Intel and its partners of bending the truth when it comes to talking up the Itanium's price advantage. "It's not true Itanium is going to come in at a lower price point," he says. "You can buy an UltraSparc system today for less than £1,000 with an unlimited server licence to support an unlimited number of users. There is a big misconception that Sun is expensive and a lot of people presented with those prices go 'Wow, I didn't know that!'"

While Intel may not be able to push UltraSparc out of the market, the arrival of Itanium means curtains for both Compaq's Alpha and HP's PA Risc platforms. Although both chips will continue to be developed over the next couple of years, they will eventually be completely replaced by Itanium.

"We are looking at continuing the development of the Alpha platform through 2004 and 2005, and running support for it with both operating system releases and our ISV community for at least another five years beyond that," says Compaq's Cochran.

In fact, Alpha customers are likely to find the chip performs better than the Itanium pretty much right up until the end of its development cycle. With support for a number of years after that, Alpha may still be a strong choice for some.

HP will provide a parallel path of PA and IA-64 processors over a similarly long period, with the PA-8800 due this year and the PA-8900 to follow in 2003. HP also says it will maintain binary compatibility across the PA-Risc family and on IA-64-based systems, but how this works in practice remains to be seen.

IBM, too, will pursue a two-track strategy, offering both Itanium systems and its own Power4 platform. The only major Unix supplier not to offer Itanium systems will be Sun. Even if UltraSparc processors can match the performance of the later, faster Itaniums, Sun will find it difficult to match the power of so many systems suppliers working on a single unified platform. Itanium customers will be able to buy from many different suppliers all selling compatible systems, whereas Sparc customers will have only a single choice.

But the Itanium is not going to be the only new 64bit chip on the market in 2002. Towards the end of the year AMD will introduce its Sledgehammer processor, which represents a complete break from Intel as far as 64bit architecture is concerned.

Instead of chucking out the x86 instruction set, AMD's 64bit offering will offer full backwards-compatibility with 32bit code alongside 64bit extensions to the instruction set. Sledgehammer will be able to run in three configurations.

A 32-bit mode will run 32bit applications on a 32-bit operating system. A compatibility mode will let 32bit apps run under a 64bit operating system without the need for a recompile. And in full 64bit mode, fully ported applications will be able to take advantage of the 64bit extensions.

"First, Sledgehammer is going to be very fast," says Simon Cole, relationships manager for AMD. "Second, it's going to be compatible with every piece of software you are running on your x86 processors and it will run them at the native speed of the chip, not in an emulated mode. It will also give you the extra RAM addresses should you need them."

AMD's problem is it doesn't have a commitment from Microsoft to port Windows to its 64bit platform. If it doesn't get this, it is likely to be left mopping up the cheaper end of the market with systems running a Sledgehammer version of Linux. Nor does it yet have any supplier commitment to the platform, although with still nearly a year to go before it debuts, is is early days.

However, AMD must overcome its lack of visibility in the current server market, otherwise there is no guarantee that systems suppliers will warm to its platform.

"As a corporation we keep on looking at AMD because we use its chips in desktop and home machines, but the general consensus from customers and our engineering arm is that at the moment there is not enough demand for AMD-based servers," says Compaq's Stevens. "That could change in the future, but when we last tried doing a server with a chip that was not Intel, it wasn't particularly successful."

Intel development rumours

However, AMD may have an even bigger problem if rumours that Intel developing its own hybrid architecture are true. This indicates that Intel may be working on a chip, codenamed Yamhill, which will run 32bit and 64bit software. If this is the case, AMD will need all the extra support it can muster.

Some support will come from Transmeta, the company behind the low-power Crusoe processor designed for mobile computers. Transmeta has licensed AMD's x86-64 technology and its HyperTransport interconnect is used on the Sledgehammer platform. It is unlikely Transmeta is eyeing up a market for 64bit x86 laptops. The company will be more interested in building a 64bit processor that appeals to manufacturers of superthin blade servers.

Transmeta's processors run cool and, as a result, generally don't require a fan. With other 64bit processors running hot, especially the Itanium, and slimline sever specialists crying out for a low-power, low-heat chip, Transmeta could sneak in the back door to capture this niche market.

PROCESSOR TIME LINE